This invention relates to separation of solids from a liquid, particularly to method of and apparatus for separation by filtration with an elastic sheet filter, wherein the solid in the liquid can be condensed and separated from the liquid to collect in a layer.
In order to collect powdered solid particles such as powdered active carbon suspended in the liquid, known is a precipitation method employing condensing agent, wherein the suspended solid particles are separated and precipitated in a precipitation tank with the aid of the condensing agent. According to the method, in addition to a high treatment cost of the suspension due to using the condensing agent of a high cost, control of injection of the condensing agent into the suspension is difficult. Further a problem of secondary public pollution may be brought about since the remaining condensing agent flows in and joins the treated liquid.
On the other hand, various solid-liquid separating apparatus using a sheet filter have been developed. Most of them, however, are directed to carry out an object to raise filtered liquid or filtrate quality, and thereby it is difficult to condense and separate to collect the filtered residue, because a large quantity of washing water is employed to wash the filter and make the filtered residue very lean.